Your architect sketches a second story and a longer kitchen wall, and the first thing the plan checker circles is not the roof — it is a 47-foot stretch of blank wall three feet inside the property line. R1 is the zone most Angelenos live in and the one they know least about, because nothing about it matters until you try to add something.
R1 is the City of Los Angeles One-Family Zone. Its core promise is simple: one house per lot, plus the accessory buildings that go with it. Its teeth are the yard requirements — a front yard of 20 percent of the lot depth, capped at 20 feet, side yards of 5 feet, and a rear yard of 15 feet (§ 12.08).
Key numbers
| R1 standard | Requirement | Where it says so |
|---|---|---|
| Front yard | 20% of lot depth, need not exceed 20 ft | § 12.08 |
| Front yard on a developed block | Average of the prevailing front yards, never more than 40 ft | § 12.08 |
| Side yard, building up to two stories | 5 ft each side | § 12.08 |
| Side yard, lot narrower than 50 ft | 10% of lot width, minimum 3 ft | § 12.08 |
| Rear yard | 15 ft | § 12.08 |
| Occupied rooftop deck, setback from the required side yard | 3 ft | § 12.08 |
| Lot size needed for accessory living quarters | 10,000 sq ft | § 12.08 |
| Lot size needed to keep horses | 20,000 sq ft, one per 5,000 sq ft | § 12.08 |
The front yard is a percentage, not a fixed number
Most people assume a setback is one figure printed somewhere. In R1 it is arithmetic with two ceilings. Start with 20 percent of the depth of your lot. On a 100-foot-deep lot that is 20 feet; on a 150-foot-deep lot it would be 30 feet, except the code says the front yard "need not exceed 20 feet." So 20 feet is the practical cap for the basic rule.
Then comes the part that surprises people on older streets. Where developed lots whose front yards vary in depth by no more than ten feet make up 40 percent or more of the frontage, the required front yard becomes the average of those existing front yards. Your neighbors' houses set your setback. If more than one such grouping exists, the code takes the combination with the shallowest average. Nothing in the paragraph can require a front yard deeper than 40 feet.
There is a separate calculation for key lots — lots whose rear line abuts the side of a corner lot — which may use the average of the adjoining interior lot's front yard and the reversed corner lot's street-side yard, applied for up to 65 feet from the rear lot line.
Side yards, and the wall-length rule nobody expects
The base number is 5 feet on each side of a main building up to two stories. Narrow lots get relief: on a lot less than 50 feet wide the side yard may shrink to 10 percent of the lot width, but never below 3 feet. Go above two stories and you add one foot to each side yard for every additional story.
Then there is the rule that catches remodels. Any portion of a building with a side wall exceeding 14 feet in height and a continuous length greater than 45 feet must have an offset — a plane break — that is at least 5 feet deep beyond the required yard and at least 10 feet long. Height for this purpose is measured from the existing or finished grade, whichever is lower, at each point along the building's perimeter. It exists to stop a two-story flat wall running the full length of a neighbor's yard, and it is why long side elevations get a notch cut into them late in design.
Outside hillside areas and the Coastal Zone, new construction has an alternative to the per-story addition: add one foot to each required side yard for each ten-foot increment, or fraction of one, above the first 18 feet of height. And an occupied rooftop deck must be set back at least 3 feet from the minimum required side yard — except on the street side of a corner lot.
The rear yard
This one is a single sentence with no arithmetic in it:
There shall be a rear yard of not less than 15 feet in depth.
— § 12.08
Accessory buildings are located under separate provisions of the code, which is why a detached garage can often sit closer to the rear line than the house can.
What else R1 lets you put on the lot
Beyond the one-family dwelling, the zone permits government-owned parks, playgrounds and community centers; accessory uses and home occupations under the city's home-occupation conditions; name plates and signs; and backyard beekeeping as an accessory use.
Accessory buildings are allowed generously but with lot-size gates. Private garages are unconditional. Accessory living quarters and servant's quarters require a lot of at least 10,000 square feet. A private stable requires 20,000 square feet and is capped at one equine per 5,000 square feet. Any combination of accessory living quarters, servant's quarters, recreation room and private garage may be housed in one building of no more than two stories.
Two other things are worth knowing. First, on lots the community plan maps as Public, Quasi-Public, Open Space or a freeway right-of-way — and on property annexed without a plan amendment — even the permitted uses need prior approval before you can proceed. Second, uses that are not on the list may still be reachable as conditional uses, which is a discretionary approval with findings rather than a counter permit (§ 12.24).
R1 is not the only one-house zone
If your property is not R1 but looks like it should be, the city has several single-family zones with different geometry. RU, the Residential Urban Zone, was written to encourage small single-family lots developed with manufactured, factory-built or site-built homes, and its front yard starts at just 10 feet (§ 12.08.1). R2, the Two-Family Zone, borrows R1's front, side and rear yards outright and changes only what may be built on the lot (§ 12.09).
What this section does not cover
The R1 section as written here sets uses and yards. It does not give you the zone's minimum lot area, its height limit, its floor area ratio, or its parking requirement — those come from other provisions of the code, from the Height District paired with your zone, and from any specific plan or overlay on your block. Do not assume a number for those from this page.
Side yard requirements in specific plans, Historic Preservation Overlay Zones and subdivision approvals also take precedence over the zone's own numbers; the zone's rules apply only where no such requirement exists. Check your parcel's designation and its overlays before you draw anything, and see our Los Angeles code overview for the wider set of local rules.
